CBSE 12 Biology Question Paper-2022 Set-3 - Practice Test
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  2. Practice Tests
  3. CBSE 12 Biology Question Paper-2022 Set-3
CBSE 12 Biology Question Paper-2022 Set-3

CBSE 12 Biology Question Paper-2022 Set-3 - Practice Test

This mock test includes actual CBSE Class 12 Biology board exam questions from the year 2022 Set-3, helping students understand exam trends and practice real paper format

2025-08-13
Pavan Pavan
CBSE Class 12 Biology 2022 Grade 12

Duration

30 min

Questions

23

Marking

Negative

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Questions Preview

Given below is the stepwise schematic representation of the process of electrophoresis. Identify the ‘alphabets’ representing (i) Anode end (ii) smallest/lightest DNA strand in the matrix (iii) Agarose gel

A
R - Anode end, T - smallest/lightest DNA strand, S - Agarose gel
B
T - Anode end, P - smallest/lightest DNA strand, R - Agarose gel
C
S - Anode end, T - smallest/lightest DNA strand, P - Agarose gel
D
P - Anode end, R - smallest/lightest DNA strand, S - Agarose gel

What is elution? State the importance of elution in this process.

A
Elution is the washing of matrix material, and it is important for final DNA separation.
B
Elution is the process of introducing samples into the agarose gel, helping to separate DNA strands.
C
Elution is the process of washing out the sample, and it helps in separating the desired molecules from the matrix.
D
Elution is the collection of DNA in the solution, important for downstream applications.

Taq polymerase after its discovery replaced E. coli DNA polymerase in PCR technique. Explain giving reasons why was the need felt for the change?

A
Taq polymerase was cheaper and more readily available than E. coli polymerase.
B
Taq polymerase was more accurate, making it ideal for PCR reactions.
C
E. coli polymerase could not function in high-temperature environments like Taq polymerase.
D
Taq polymerase is heat-stable, allowing for high-temperature PCR reactions, which was not possible with E. coli polymerase.

What are cry-proteins? With the help of a suitable example, explain how it acts as a biological pesticide.

A
Cry-proteins are antibodies used to control plant diseases caused by viruses.
B
Cry-proteins are plant-based proteins that defend crops from fungi and pests.
C
Cry-proteins are synthetic chemicals used to prevent pest damage in crops.
D
Cry-proteins are toxic proteins produced by bacteria, which act as a biological pesticide by killing specific pests.

Explain the concept of ‘co-extinction’ by taking two examples.

A
Co-extinction occurs when two species evolve together, sharing a mutual relationship.
B
Co-extinction is when species become extinct together due to shared environmental changes.
C
Co-extinction occurs when the extinction of one species leads to the extinction of another species that depends on it.
D
Co-extinction is when both species are extinct due to a genetic mutation.

Write the complete name of the diagnostic test for AIDS. Explain the principle it works on.

A
Enzyme-linked immunosorbent assay (ELISA) works by detecting the antibodies produced in response to the HIV infection.
B
Polymerase chain reaction (PCR) works by amplifying the viral DNA to detect HIV.
C
Western blot test works by detecting proteins associated with the virus.
D
Rapid diagnostic tests work by detecting HIV antigens in the blood.

A patient complains of suffering from constipation, stomach ache, stool with blood clots and excess mucous. The physician diagnosed it as amoebiasis, after stool test. Write the scientific name of the microbe identified in the stool sample.

A
Plasmodium falciparum
B
Giardia lamblia
C
Entamoeba histolytica
D
Trichomonas vaginalis

Mammals are capable of maintaining homeostasis. But, very few smaller animals can survive in polar regions. Give reasons.

A
Smaller animals have a lower metabolic rate, which helps them to conserve heat.
B
Smaller animals have thick fur that keeps them warm in colder regions.
C
Smaller animals have a higher surface area to volume ratio, leading to higher heat loss in cold environments.
D
Smaller animals are more adaptable to cold climates due to their ability to hibernate.

Write the inference drawn by Alexander von Humboldt after his extensive explorations of South American jungle.

A
Species richness increases with the increase in area, and environmental factors play a significant role in shaping biodiversity.
B
Species richness is highly influenced by human activities, leading to environmental degradation.
C
Species richness decreases with the increase in altitude, showing a clear inverse relationship.
D
Species richness is not affected by the area and remains constant across different geographical regions.

Explain the concept of ‘co-extinction’ by taking two examples.

A
Co-extinction occurs when the extinction of one species leads to the extinction of another species that depends on it.
B
Co-extinction is when species become extinct together due to shared environmental changes.
C
Co-extinction occurs when two species evolve together, sharing a mutual relationship.
D
Co-extinction is when both species are extinct due to a genetic mutation.

What is the scientific name of the plant from where natural cannabinoids are obtained?

A
Eucalyptus globulus
B
Cannabis sativa
C
Coffea arabica
D
Humulus lupulus

What is the primary function of a primer in PCR?

A
To inhibit the activity of Taq polymerase.
B
To split the DNA strands during denaturation.
C
To stabilize the DNA sample.
D
To provide a starting point for DNA synthesis.

Explain the concept of “forest extinction” by taking two examples.

A
Forest extinction occurs when a forest ecosystem is lost, causing the extinction of species that depend on it.
B
Forest extinction is when trees become extinct due to climate change.
C
Forest extinction happens when only smaller species go extinct in a forest ecosystem.
D
Forest extinction is when forests provide food but not shelter for wildlife.

What is the relationship between the area and species richness according to Alexander von Humboldt?

A
Species richness increases with the increase in area.
B
Species richness decreases with the increase in area.
C
Species richness remains constant regardless of area.
D
Species richness is unaffected by area size.

What are the main advantages of using Trichoderma and Baculovirus as biological control agents?

A
They help control pests without harming crops or the environment.
B
They are less effective than synthetic chemicals in pest control.
C
They can only target a few species of pests.
D
They are resistant to environmental changes and global warming.

How does our body combat allergic reactions, such as those caused by entering an air-conditioned room after playing football?

A
By triggering an immune response involving histamines to protect the body.
B
By decreasing the production of mucus to clear allergens.
C
By neutralizing the allergic reaction through the release of insulin.
D
By suppressing the symptoms through immediate blood clotting.

Which of the following best describes the role of Rhizobium in improving soil fertility?

A
Rhizobium fixes nitrogen from the atmosphere into a form that plants can use.
B
Rhizobium breaks down organic material into nutrients.
C
Rhizobium improves soil texture and drainage.
D
Rhizobium protects plants from fungal infections.

Which of the following organisms is most commonly used by organic farmers for biological control?

A
Trichoderma
B
E. coli
C
Bacillus thuringiensis
D
Rhizobium

What is the role of Baculovirus in crop protection?

A
Baculovirus acts as a biological pesticide targeting specific insect pests.
B
Baculovirus helps to increase plant immunity against viral diseases.
C
Baculovirus promotes soil fertility by breaking down organic matter.
D
Baculovirus strengthens plant cells to resist fungal infections.

How does the human body combat allergic reactions when exposed to allergens?

A
The body produces histamines to trigger an immune response.
B
The body produces insulin to balance immune activity.
C
The body uses a cooling mechanism to remove allergens.
D
The body activates blood clotting to prevent spread of allergens.

What is the significance of using biological control agents like Trichoderma and Baculovirus in farming?

A
They reduce the reliance on chemical pesticides, promoting sustainable farming.
B
They are used to improve the nutritional content of crops.
C
They are used to enhance the yield of crops by controlling weeds.
D
They are used to decrease water usage in farming practices.

Which of the following explains why smaller animals find it difficult to survive in polar regions?

A
Smaller animals have a higher surface area to volume ratio, leading to excessive heat loss.
B
Smaller animals are not adapted to cold climates and lack the ability to hibernate.
C
Smaller animals have high metabolic rates, which make them susceptible to freezing.
D
Smaller animals cannot find enough food in polar regions to survive.

Which type of pyramid is represented by the given diagram?

A
Age pyramid
B
Energy pyramid
C
Biomass pyramid
D
Pyramid of numbers